[dpdk-dev] [PATCH v6 0/6] add Tx preparation
Ananyev, Konstantin
konstantin.ananyev at intel.com
Tue Oct 18 14:28:52 CEST 2016
>
> As discussed in that thread:
>
> http://dpdk.org/ml/archives/dev/2015-September/023603.html
>
> Different NIC models depending on HW offload requested might impose different requirements on packets to be TX-ed in terms of:
>
> - Max number of fragments per packet allowed
> - Max number of fragments per TSO segments
> - The way pseudo-header checksum should be pre-calculated
> - L3/L4 header fields filling
> - etc.
>
>
> MOTIVATION:
> -----------
>
> 1) Some work cannot (and didn't should) be done in rte_eth_tx_burst.
> However, this work is sometimes required, and now, it's an
> application issue.
>
> 2) Different hardware may have different requirements for TX offloads,
> other subset can be supported and so on.
>
> 3) Some parameters (e.g. number of segments in ixgbe driver) may hung
> device. These parameters may be vary for different devices.
>
> For example i40e HW allows 8 fragments per packet, but that is after
> TSO segmentation. While ixgbe has a 38-fragment pre-TSO limit.
>
> 4) Fields in packet may require different initialization (like e.g. will
> require pseudo-header checksum precalculation, sometimes in a
> different way depending on packet type, and so on). Now application
> needs to care about it.
>
> 5) Using additional API (rte_eth_tx_prep) before rte_eth_tx_burst let to
> prepare packet burst in acceptable form for specific device.
>
> 6) Some additional checks may be done in debug mode keeping tx_burst
> implementation clean.
>
>
> PROPOSAL:
> ---------
>
> To help user to deal with all these varieties we propose to:
>
> 1) Introduce rte_eth_tx_prep() function to do necessary preparations of
> packet burst to be safely transmitted on device for desired HW
> offloads (set/reset checksum field according to the hardware
> requirements) and check HW constraints (number of segments per
> packet, etc).
>
> While the limitations and requirements may differ for devices, it
> requires to extend rte_eth_dev structure with new function pointer
> "tx_pkt_prep" which can be implemented in the driver to prepare and
> verify packets, in devices specific way, before burst, what should to
> prevent application to send malformed packets.
>
> 2) Also new fields will be introduced in rte_eth_desc_lim:
> nb_seg_max and nb_mtu_seg_max, providing an information about max
> segments in TSO and non-TSO packets acceptable by device.
>
> This information is useful for application to not create/limit
> malicious packet.
>
>
> APPLICATION (CASE OF USE):
> --------------------------
>
> 1) Application should to initialize burst of packets to send, set
> required tx offload flags and required fields, like l2_len, l3_len,
> l4_len, and tso_segsz
>
> 2) Application passes burst to the rte_eth_tx_prep to check conditions
> required to send packets through the NIC.
>
> 3) The result of rte_eth_tx_prep can be used to send valid packets
> and/or restore invalid if function fails.
>
> e.g.
>
> for (i = 0; i < nb_pkts; i++) {
>
> /* initialize or process packet */
>
> bufs[i]->tso_segsz = 800;
> bufs[i]->ol_flags = PKT_TX_TCP_SEG | PKT_TX_IPV4
> | PKT_TX_IP_CKSUM;
> bufs[i]->l2_len = sizeof(struct ether_hdr);
> bufs[i]->l3_len = sizeof(struct ipv4_hdr);
> bufs[i]->l4_len = sizeof(struct tcp_hdr);
> }
>
> /* Prepare burst of TX packets */
> nb_prep = rte_eth_tx_prep(port, 0, bufs, nb_pkts);
>
> if (nb_prep < nb_pkts) {
> printf("tx_prep failed\n");
>
> /* nb_prep indicates here first invalid packet. rte_eth_tx_prep
> * can be used on remaining packets to find another ones.
> */
>
> }
>
> /* Send burst of TX packets */
> nb_tx = rte_eth_tx_burst(port, 0, bufs, nb_prep);
>
> /* Free any unsent packets. */
>
>
> v5 changes:
> - rebased csum engine modification
> - added information to the csum engine about performance tests
> - some performance improvements
>
> v4 changes:
> - tx_prep is now set to default behavior (NULL) for simple/vector path
> in fm10k, i40e and ixgbe drivers to increase performance, when
> Tx offloads are not intentionally available
>
> v3 changes:
> - reworked csum testpmd engine instead adding new one,
> - fixed checksum initialization procedure to include also outer
> checksum offloads,
> - some minor formattings and optimalizations
>
> v2 changes:
> - rte_eth_tx_prep() returns number of packets when device doesn't
> support tx_prep functionality,
> - introduced CONFIG_RTE_ETHDEV_TX_PREP allowing to turn off tx_prep
>
>
> Tomasz Kulasek (6):
> ethdev: add Tx preparation
> e1000: add Tx preparation
> fm10k: add Tx preparation
> i40e: add Tx preparation
> ixgbe: add Tx preparation
> testpmd: use Tx preparation in csum engine
>
> app/test-pmd/csumonly.c | 36 ++++------
> config/common_base | 1 +
> drivers/net/e1000/e1000_ethdev.h | 11 +++
> drivers/net/e1000/em_ethdev.c | 5 +-
> drivers/net/e1000/em_rxtx.c | 48 ++++++++++++-
> drivers/net/e1000/igb_ethdev.c | 4 ++
> drivers/net/e1000/igb_rxtx.c | 52 ++++++++++++++-
> drivers/net/fm10k/fm10k.h | 6 ++
> drivers/net/fm10k/fm10k_ethdev.c | 5 ++
> drivers/net/fm10k/fm10k_rxtx.c | 50 +++++++++++++-
> drivers/net/i40e/i40e_ethdev.c | 3 +
> drivers/net/i40e/i40e_rxtx.c | 72 +++++++++++++++++++-
> drivers/net/i40e/i40e_rxtx.h | 8 +++
> drivers/net/ixgbe/ixgbe_ethdev.c | 3 +
> drivers/net/ixgbe/ixgbe_ethdev.h | 5 +-
> drivers/net/ixgbe/ixgbe_rxtx.c | 58 +++++++++++++++-
> drivers/net/ixgbe/ixgbe_rxtx.h | 2 +
> lib/librte_ether/rte_ethdev.h | 85 +++++++++++++++++++++++
> lib/librte_mbuf/rte_mbuf.h | 9 +++
> lib/librte_net/Makefile | 3 +-
> lib/librte_net/rte_pkt.h | 137 ++++++++++++++++++++++++++++++++++++++
> 21 files changed, 572 insertions(+), 31 deletions(-)
> create mode 100644 lib/librte_net/rte_pkt.h
>
> --
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
> 1.7.9.5
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